Multi-ary error-correcting code transmitting and receiving apparatuse, data transmission system, and relevant method

ABSTRACT

The embodiments of the present invention disclose an apparatus for transmitting multi-ary error-correcting codes, an apparatus for receiving multi-ary error-correcting codes, a data transmission system, and relevant methods to simplify operations. The apparatus for transmitting multi-ary error-correcting codes includes: a multi-ary channel encoder, adapted to perform multi-ary coding for source data frames of a user to obtain encoded sequences; a symbol mapper, adapted to perform symbol mapping for the encoded sequences to obtain symbol sequences; and a spreading and interleaving unit, adapted to spread and interleave the symbol sequences. Moreover, a corresponding apparatus for receiving multi-ary error-correcting codes, a data transmission system, and relevant methods are provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2008/072876, filed on Oct. 30, 2008, which claims priority toChinese Patent Application No. 200710166505.5, filed on Nov. 2, 2007,both of which are hereby incorporated by reference in their entireties.

FIELD OF THE INVENTION

The present invention relates to the data encoding and decoding field,and in particular, to an apparatus for transmitting multi-aryerror-correcting codes, an apparatus for receiving multi-aryerror-correcting codes, a data transmission system, and relevantmethods.

BACKGROUND

The existing communication system involves different methods of MultipleAccess, for example, Code Division Multiple Access (CDMA) and InterleaveDivision Multiple Access (IDMA). The CDMA means that different users usedifferent spread code sequences to transmit information, and the IDMAmeans that different users use different interleavers to transmitinformation.

In the CDMA technology, the Forward Error Correction (FEC) isconcatenated with spreading operation on the transmitter side. From theperspective of the channel coding theory, the spreading operation doesnot obtain any coding gain, and the IDMA technology substitutes low bitrate FEC for the concatenation between the FEC and the spreadingoperation in the CDMA technology. Therefore, the coding gain can bemaximized. In both theory and practice, it is proved that the IDMAtechnology provides higher spectrum utilization ratio compared with theCDMA technology.

In the prior art, the IDMA-based data transmission solution employsbinary codes. For details, see FIG. 1 and FIG. 2.

FIG. 1 shows an IDMA transmitter apparatus under high-order modulationin the prior art. The apparatus includes a binary encoder 101, aspreader 102, an interleaver 103, and a symbol mapper 104. The detailedprocess is as follows:

The user source data frame is processed by the binary encoder 101 intoan encoded sequence, the encoded sequence is processed by the spreader102 into a spreading sequence, the spreading sequence is processed bythe interleaver 103 into an interleaved sequence, and the interleavedsequence is processed by the symbol mapper 104 into a symbol sequence,which is then sent out.

FIG. 2 shows an IDMA receiver apparatus under high-order modulation inthe prior art. The apparatus includes a multi-user demodulator 201, asymbol-bit probability converting unit 202, a de-interleaver 203, ade-spreader 204, a binary decoder 205, a spreader 206, an interleaver207, and a bit-symbol probability converting unit 208. The detailedprocess is as follows:

In the forward link, the multi-user demodulator 201 calculates thesymbol posteriori probability information for the received symbolsequence. The symbol posteriori probability information is processed bythe symbol-bit probability converting unit 202 into bit posterioriprobability information, and the bit posteriori probability informationis processed by the de-interleaver 203 and the de-spreader 204, and theninput to the binary decoder 205 for decoding.

In the reverse link, the binary decoder 205 outputs the bit prioriprobability information of the encoded sequence to the spreader 206. Thespread bit priori probability information after being spread by thespreader 206 passes through the interleaver 207, and is input to thebit-symbol probability converting unit 208. The bit priori probabilityinformation is converted into symbol priori probability information,which is sent to the multi-user demodulator 201 again for the nextiterative operation until the preset maximum iterative count is met.

The prior art reveals that: First, binary codes are used for datatransmission in the prior art, but the binary codes are not much capableof error correction or resisting burst errors; second, in thetransmitter solution in the prior art, after passing through thespreader and the interleaver, the encoded bit data is mapped to symboldata for sending. Because the number of data units of the bit data isgreater than the number of data units of the symbol data, the spreaderand the interleaver need to perform plenty of operations, thus leadingto much complexity of operation in the prior art.

Further, in the receiver solution in the prior art, the data istransmitted in the binary code mode, namely, the binary decoder canidentify only the bit probability information. Therefore, the receiverneeds to convert the symbol probability information into bit probabilityinformation after receiving the symbol sequence and calculating out thesymbol probability information of the symbol sequence, and then theinformation can be referred to the binary decoder. Likewise, the binarydecoder outputs bit probability information, which needs iteration, andthe bit probability information needs to be converted into symbolprobability information. Therefore, in the case of high-ordermodulation, the receiver needs to perform frequent conversion betweenthe symbol probability information and the bit probability information,thus leading to much complexity of operation.

Further still, in the conversion between the symbol probabilityinformation and the bit probability information, information may belost, the coding gain is partially lost, and the system performance isaffected.

SUMMARY

The embodiments of the present invention provide an apparatus fortransmitting multi-ary error-correcting codes, an apparatus forreceiving multi-ary error-correcting codes, a data transmission system,and relevant methods.

An apparatus for transmitting multi-ary error-correcting codes providedin an embodiment of the present invention includes:

a multi-ary channel encoder, adapted to perform multi-ary encoding forsource data frames of a user to obtain encoded sequences;

a symbol mapper, adapted to perform symbol mapping for the encodedsequences to obtain symbol sequences; and

a spreading and interleaving unit, adapted to spread and interleave thesymbol sequences.

An apparatus for transmitting multi-ary error-correcting codes providedin an embodiment of the present invention includes:

a multi-ary channel encoder, adapted to perform multi-ary coding forsource data frames of a user to obtain encoded sequences;

a grouping device, adapted to group the encoded sequences to obtaingrouped sequences;

a user interleaver, adapted to interleave the grouped sequences toobtain interleaved sequences;

a symbol mapper, adapted to perform symbol mapping for the interleavedsequences to obtain symbol sequences; and

a spreader, adapted to spread the symbol sequences to obtain spreadingsequences.

An apparatus for receiving multi-ary error-correcting codes provided inan embodiment of the present invention includes:

a multi-user demodulator, adapted to receive sequences and calculate thereceived sequences to obtain symbol posteriori probability sequences;

a de-spreading and de-interleaving unit, adapted to perform de-spreadingand de-interleaving for the symbol posteriori probability sequences;

a multi-ary decoder, adapted to decode the de-spread and de-interleavedsequences, output symbol priori probability sequences, work with themulti-user demodulator to perform iterative operations, judge whether acount of iterations reaches a preset threshold, and output decodingresults if the count of the iterations reaches the preset threshold; and

a spreading and interleaving unit, adapted to spread and interleave thesymbol priori probability sequences, and send the spread and interleavedsequences to the multi-user demodulator.

A data transmission system provided in an embodiment of the presentinvention includes an apparatus for transmitting multi-aryerror-correcting codes and an apparatus for receiving multi-aryerror-correcting codes.

The apparatus for transmitting multi-ary error-correcting codesincludes:

a multi-ary channel encoder, adapted to perform multi-ary encoding forsource data frames of a user to obtain encoded sequences;

a symbol mapper, adapted to perform symbol mapping for the encodedsequences to obtain symbol sequences; and

a spreading and interleaving unit, adapted to spread and interleave thesymbol sequences;

The apparatus for receiving multi-ary error-correcting codes includes:

a multi-user demodulator, adapted to receive sequences and calculate thereceived sequences to obtain symbol posteriori probability sequences;

a de-spreading and de-interleaving unit, adapted to perform de-spreadingand de-interleaving for the symbol posteriori probability sequences;

a multi-ary decoder, adapted to: decode the de-spread and de-interleavedsequences, output symbol priori probability sequences, work with themulti-user demodulator to perform iterative operations, judge whether acount of iterations reaches a preset threshold, and output decodingresults if the count of the iterations reaches the preset threshold; and

a spreading and interleaving unit, adapted to spread and interleave thesymbol priori probability sequences, and send the spread and interleavedsequences to the multi-user demodulator.

A method for transmitting multi-ary error-correcting codes provided inan embodiment of the present invention includes:

performing multi-ary coding for source data frames of a user to obtainencoded sequences;

performing symbol mapping for the encoded sequences to obtain symbolsequences; and

preprocessing the symbol sequences; and transmitting the preprocessedsequences.

A method for receiving multi-ary error-correcting codes provided in anembodiment of the present invention includes:

calculating received sequences to obtain symbol posteriori probabilitysequences;

de-spreading the symbol posteriori probability sequences to obtainde-spread symbol posteriori probability sequences;

de-interleaving the de-spread symbol posteriori probability sequences toobtain de-interleaved symbol posteriori probability sequences;

decoding the de-interleaved symbol posteriori probability sequences,outputting symbol priori probability sequences, working with amulti-user demodulator to perform iterative operations, judging whethera count of iterations reaches a preset threshold, and outputtingdecoding results if the count of the iterations reaches the presetthreshold;

interleaving the symbol priori probability sequences to obtaininterleaved symbol priori probability sequences; and

spreading the interleaved symbol priori probability sequences to obtainspread symbol priori probability sequences, and sending the spreadsymbol priori probability sequences to the multi-user demodulator toundergo joint iterative operations.

A method for receiving multi-ary error-correcting codes provided in anembodiment of the present invention includes:

calculating received sequences to obtain symbol posteriori probabilitysequences;

de-interleaving the symbol posteriori probability sequences to obtainde-interleaved symbol posteriori probability sequences;

de-spreading the de-interleaved symbol posteriori probability sequencesto obtain de-spread symbol posteriori probability sequences;

decoding the de-spread symbol posteriori probability sequences,outputting symbol priori probability sequences, working with amulti-user demodulator to perform iterative operations, judging whethera count of iterations reaches a preset threshold, and outputtingdecoding results if the count of the iterations reaches the presetthreshold;

spreading the symbol priori probability sequences to obtain spreadsymbol priori probability sequences; and

interleaving the spread symbol priori probability sequences to obtaininterleaved symbol priori probability sequences, and sending theinterleaved symbol priori probability sequences to the multi-userdemodulator to undergo joint iterative operations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an IDMA transmitter apparatus under high-order modulationin the prior art;

FIG. 2 shows an IDMA receiver apparatus under high-order modulation inthe prior art;

FIG. 3 shows an apparatus for transmitting multi-ary error-correctingcodes in the first embodiment of the present invention;

FIG. 4 shows an apparatus for receiving multi-ary error-correcting codesin the first embodiment of the present invention;

FIG. 5 shows an apparatus for transmitting multi-ary error-correctingcodes in the second embodiment of the present invention;

FIG. 6 shows an apparatus for receiving multi-ary error-correcting codesin the second embodiment of the present invention;

FIG. 7 shows an apparatus for transmitting multi-ary error-correctingcodes in the third embodiment of the present invention;

FIG. 8 shows an apparatus for receiving multi-ary error-correcting codesin the third embodiment of the present invention;

FIG. 9 shows an apparatus for transmitting multi-ary error-correctingcodes in the fourth embodiment of the present invention;

FIG. 10 shows an apparatus for transmitting multi-ary error-correctingcodes in the fifth embodiment of the present invention;

FIG. 11 is an overall schematic diagram of an apparatus for receivingmulti-ary error-correcting codes in an embodiment of the presentinvention;

FIG. 12 is a flowchart of a method for transmitting multi-aryerror-correcting codes in the first embodiment of the present invention;

FIG. 13 is a flowchart of a method for transmitting multi-aryerror-correcting codes in the second embodiment of the presentinvention;

FIG. 14 is a flowchart of a method for receiving multi-aryerror-correcting codes in the first embodiment of the present invention;and

FIG. 15 is a flowchart of a method for receiving multi-aryerror-correcting codes in the second embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The embodiments of the present invention provide an apparatus fortransmitting multi-ary error-correcting codes, an apparatus forreceiving multi-ary error-correcting codes, a data transmission system,and relevant methods to simplify operation.

The embodiments of the present invention perform data transmission basedon multi-my codes (namely, multi-ary error-correcting codes) encodingand decoding. Multi-ary codes refer to multi-ary error-correcting codesbased on high-order Finite Field structures. If a field includes afinite number of elements, the domain is called a Finite Field (e.g.Galois Field, GF).

Research indicates that the performance of multi-ary codes is betterthan the performance of the traditional binary codes. Therefore, theembodiments of the present invention provides better error correctionperformance and is more capable of resisting burst errors and moresuitable for high-rate transmission.

Based on the multi-ary codes, multiple modes of transmitting andreceiving multi-ary error-correcting codes are provided herein, asdetailed below.

As shown in FIG. 3, an apparatus for transmitting multi-aryerror-correcting codes in the first embodiment of the present inventionincludes:

a multi-ary channel encoder 301, adapted to perform multi-ary coding forsource data frames of a user to obtain encoded sequences;

a symbol mapper 302, adapted to perform symbol mapping for the encodedsequences to obtain symbol sequences;

a spreader 303, adapted to spread the symbol sequences to obtainspreading sequences; and

a user interleaver 304, adapted to interleave the spreading sequences toobtain interleaved sequences.

The detailed transmitting process in this embodiment is as follows:

Assume that the source data frames input by a user k are b_(k)={b_(k,0),b_(k,1), . . . , b_(k,m), . . . }, and b_(k) is processed by a multi-arychannel encoder 301 into a encoded sequence c_(k), where m representsthe serial number of the encoded sequence.

The structure of the multi-ary channel encoder 301 and the encodingprocess are covered by the prior art, and are not repeated here anyfurther.

It is to be noted that in a traditional IDMA system, the channel encoderin use is based on binary codes, and the encoded sequence is a bit-levelsequence, namely, the sequence is composed of separate bits. Thissequence is still a bit-level sequence after being processed by thespreader.

When the channel encoder used by the transmitter apparatus is based onmulti-ary codes, the sequence output by the multi-ary channel encoder301 is not a simple bit-level sequence, but an element composed ofseveral bits. Several elements make up an encoded sequencec_(k)={c_(k,0), c_(k,1), . . . , c_(k,m), . . . }.

It is assumed that the multi-ary channel encoder is defined on a Galoisfield GF(2^(q)) where q is a natural number. Every q continuous bits inthe encoded sequence c_(k) corresponds to a specific symbol.Specifically, after c_(k) passes through the symbol mapper 302, a symbolsequence s_(k)={s_(k,0), s_(k,1), . . . , s_(k,m), . . . } is output.

The operation corresponding to the symbol mapper 302 is to map every qcontinuous bits in the encoded sequence c_(k) to a symbol, namely, map{c_(k,qm), c_(k,qm+1), c_(k,qm+q−1)} to a symbol {s_(k,m)} (m=0, 1, . .. ). Therefore, the length of the symbol sequence s_(k) output by thesymbol mapper 302 is equal to 1/q of the length of the encoded sequencec_(k) input to the symbol mapper 301.

In the existing solution based on binary codes, the source data framesof the user are binary-encoded first to generate bit-level encodedsequences (namely, each element in the encoded sequence is a bit). Thesymbol mapper maps several bit-level elements to a symbol. In thisembodiment, however, the source data frames of the user are multi-aryencoded first. In the generated encoded sequences, each element is nolonger a separate bit, but an element composed of several bits andgenerated in the multi-ary encoding process. The symbol mapper maps suchseveral elements to a symbol, as a result, it can reduce the data aftermapping and simplify the subsequent calculation.

The symbol mapper 302 inputs the symbol sequence s_(k) to a spreader 303for spreading spectrum to obtain a spreading sequence v_(k)={v_(k,0),v_(k,1), . . . , v_(k,L−1)}. The spreading sequence v_(k)={v_(k,0),v_(k,1), . . . , v_(k,L−1)} indicates a spreading sequence obtainedafter the symbol sequence of user k is spread by the spreader 303, withthe length being L.

The spreading sequence is input to the user interleaver 304 forinterleaving to obtain an interleaved sequence x_(k)={x_(k,0), x_(k,1),. . . , x_(k,L−1)}. The interleaved sequence x_(k)={x_(k,0), x_(k,1), .. . , x_(k,L−1)} indicates a sequence obtained after the spreadingsequence of user k is interleaved by the user interleaver 304, with thelength being L. The user interleaver 304 used in this embodiment may bethe same as or different from the interleaver in the existing IDMAsystem. When all users use the same spreader, the users need to usedifferent interleavers; when the users use different spreaders, theusers may use the same or different interleavers.

In this embodiment, the multi-ary codes transmitting process alsoinvolves a spreading spectrum process and an interleaving process, thespreading spectrum means the bandwidth of the channel occupied by thetransmitted signal is much wider than the minimum bandwidth required bythe information, and the interleaving means rearranging the encodedsignals according to certain rules, generally based on different users,therefore, after the interleaving, the signals sent by different userscan be identified effectively. The spreading spectrum process and theinterleaving process in this embodiment improve the efficiency oftransmitting multi-ary codes.

In this embodiment, the symbol mapping is performed before spreading andinterleaving, thus it can reduce the data units and simplify theoperations of spreading and interleaving.

Corresponding to the foregoing transmitting apparatus, as shown in FIG.4, an apparatus for receiving multi-ary error-correcting codes in thefirst embodiment of the present invention includes:

a multi-user demodulator 401, adapted to receive sequences and calculatethe received sequences to obtain symbol posteriori probabilitysequences;

a de-interleaver 402, adapted to de-interleave the symbol probabilitysequences to obtain de-interleaved symbol posteriori probabilitysequences;

a de-spreader 403, adapted to de-spread the de-interleaved symbolposteriori probability sequences to obtain de-spread symbol posterioriprobability sequences;

a multi-ary decoder 404, adapted to: decode the de-spread symbolposteriori probability sequences, output symbol priori probabilitysequences, work with a multi-user demodulator 401 to perform iterativeoperations, judge whether the count of iterations reaches a presetthreshold, and output decoding results if the count of iterationsreaches the preset threshold;

a spreader 405, adapted to spread the symbol priori probabilitysequences to obtain spread symbol priori probability sequences; and

a user interleaver 406, adapted to interleave the spread symbol prioriprobability sequences to obtain interleaved symbol priori probabilitysequences.

The apparatus for receiving multi-ary error-correcting codes in thisembodiment includes two links: a forward link and a reverse link. Thereceiving apparatus needs to perform iterative operation decodingthrough the forward link and the reverse link, and output the decodingresults when the preset condition is fulfilled. The preset condition inthis embodiment refers to the count of iterative operations reaches thepreset threshold while the multi-user demodulator 401 and the multi-arydecoder 404 perform the demodulation and decoding process cyclically.The receiving process is detailed below.

In the forward link, the received signal is sent to the multi-userdemodulator 401 to calculate an estimate value of the symbol sequencex_(k)={x_(k,0), x_(k,1), . . . , x_(k,L−1)} to user k. The estimatevalue is {e_(ese)(x_(k)(j))}, where j represents the serial number ofthe received sequence. The estimate value is a probability sequence,namely, a symbol posteriori probability sequence, which is composed ofthe posteriori probability value of every transmitted symbol. Thecalculation method is covered by the prior art.

This embodiment uses a single user (user k) as an example. In practice,a multi-user demodulator 401 may process the symbol sequences sent bymultiple users.

After the {e_(ese)(x_(k)(j))} passes through the de-interleaver 402, ade-interleaved sequence {e_(ese)(v_(k)(j))} is output.

The process executed by the de-interleaver 402 is an inverse of theprocess executed by the user interleaver 304 in FIG. 3. After the{e_(ese)(v_(k)(j))} sequence passes through the de-spreader 403, ade-spreading sequence {e_(ese)(s_(k)(j))} is output.

The process executed by the de-spreader 403 is an inverse of the processexecuted by the spreader 303 in FIG. 3, and the detailed process iscovered by the prior art.

The {e_(ese)(s_(k)(j))} sequence is sent to the multi-ary decoder 404directly.

The multi-ary decoder 404 is adapted to: decode the de-interleavedsymbol posteriori probability sequences, output symbol prioriprobability sequences, work with a multi-user demodulator 401 to performiterative operations, judge whether the count of iterations reaches apreset threshold, and output decoding results if the count of iterationsreaches the preset threshold.

As the multi-ary decoder 404 can process the multi-ary error-correctingcodes, and identify the symbol posteriori probability, which does notneed to be converted into the bit posteriori probability, therefore, theoperation is simplified.

In the prior art based on binary codes, each symbol in the symbolsequence transmitted by the transmitter is composed of several bit-levelelements; the receiver includes the corresponding binary decoder; aftercalculating out the symbol posteriori probability sequence according tothe symbol sequence transmitted by the user, the multi-user demodulatorneeds to convert the symbol posteriori probability sequence into the bitposteriori probability sequence so that the probability sequence isidentifiable to the binary decoder. In this embodiment, multi-ary codesare used in the transmitter, and the receiver includes the correspondingmulti-ary decoder 404; after calculating out the symbol posterioriprobability sequence according to the symbol sequence transmitted by theuser, the multi-user demodulator 401 can recover the symbol posterioriprobability sequence and send it to the multi-ary decoder 404 fordecoding, without involving any conversion of the probability sequence,and therefore, the operation is simplified.

In the reverse link, the multi-ary decoder 404 outputs an estimate valueof the transmitted symbol sequence. The estimate value is{e_(dec)(s_(k)(j))}, which is a probability sequence, namely, a symbolpriori probability sequence composed of the priori probability value ofevery transmitted symbol. The calculation method is covered by the priorart.

After the {e_(dec)(s_(k)(j))} passes through the spreader 405, a spreadsymbol priori probability sequence {e_(dec)(v_(k)(j))} is output.

The spreader 405 may be the same as the spreader 303 in FIG. 3.

After the {e_(dec)(v_(k)(j))} passes through the user interleaver 406,an interleaved symbol priori probability sequence {e_(dec)(x_(k)(j))} isoutput. The user interleaver 406 may be the same as the user interleaver304 in FIG. 3.

The {e_(dec)(x_(k)(j))} is sent to the multi-user demodulator 401 forthe next iterative operation.

The foregoing process recurs iteratively until the count of iterationsreaches the preset threshold, whereupon the multi-ary decoder 404outputs a decision value of the user source data frame.

The apparatus for transmitting multi-ary error-correcting codes iscombined with the apparatus for receiving multi-ary error-correctingcodes into a data transmission system.

The order of transmitting process executed by the transmitting apparatusin the foregoing embodiment is: first decoding, then mapping, thenspreading spectrum, then interleaving, and transmitting. It isunderstandable that after the decoding and the mapping, the interleavingmay occur before the spreading spectrum and the transmitting, as shownin FIG. 5. FIG. 5 shows an apparatus for transmitting multi-aryerror-correcting codes in the second embodiment of the presentinvention. The transmitting apparatus includes:

a multi-ary channel encoder 501, adapted to perform multi-ary coding forsource data frames of a user to obtain encoded sequences;

a symbol mapper 502, adapted to perform symbol mapping for the encodedsequences to obtain symbol sequences, where: in the existing solutionbased on binary codes, the source data frames of the user arebinary-encoded first to generate bit-level encoded sequences (namely,each element in the encoded sequences is a bit). The symbol mapper mapsseveral bit-level elements into a symbol. In this embodiment, however,the source data frames of the user are multi-ary encoded first. In thegenerated encoded sequences, each element is no longer a separate bit,but an element composed of several bits and generated in the multi-arycoding process. The symbol mapper maps such several elements to asymbol, as a result, it can reduce the data after mapping and simplifythe subsequent calculation;

a user interleaver 503, adapted to interleave the symbol sequences toobtain interleaved sequences, where the users may use the same ordifferent user interleavers; and

a spreader 504, adapted to spread the interleaved sequences to obtainspreading sequences, where the users use different spreaders.

The detailed transmitting process differs from the first embodiment ofthe transmitting apparatus only in that the order of the interleavingstep and the spreading step is changed.

In this embodiment, the multi-ary code transmitting process includes aspreading process and an interleaving process, thus improving theefficiency of transmitting the multi-ary codes.

Likewise, the receiving apparatus needs to be changed accordingly, asshown in FIG. 6. FIG. 6 shows an apparatus for receiving multi-aryerror-correcting codes in the second embodiment of the presentinvention. The receiving apparatus includes:

a multi-user demodulator 601, adapted to receive sequences and calculatethe received sequences to obtain symbol posteriori probabilitysequences;

a de-spreader 602, adapted to de-spread the symbol posterioriprobability sequences to obtain de-spread symbol posteriori probabilitysequences, where the process executed by the de-spreader 602 is aninverse of the process executed by the spreader 504 in FIG. 5, and thedetailed process is covered by the prior art;

a de-interleaver 603, adapted to de-interleave the de-spread symbolposteriori probability sequences to obtain de-interleaved symbolposteriori probability sequences, where the process executed by thede-interleaver 603 is an inverse of the process executed by theinterleaver 503 in FIG. 5, and the detailed process is covered by theprior art;

a multi-ary decoder 604, adapted to decode the de-interleaved symbolposteriori probability sequences, output symbol priori probabilitysequences, work with a multi-user demodulator 601 to perform iterativeoperations, judge whether the count of iterations reaches a presetthreshold, and output decoding results if the count of iterationsreaches the preset threshold, where: in the prior art based on binarycodes, each symbol in the symbol sequence transmitted by the transmitteris composed of several bit-level elements; the receiver includes thecorresponding binary decoder; after calculating out the symbolposteriori probability sequence according to the symbol sequencetransmitted by the user, the multi-user demodulator needs to convert thesymbol posteriori probability sequence into the bit posterioriprobability sequence so that the probability sequence is identifiable tothe binary decoder. In this embodiment, multi-ary codes are used in thetransmitter, and the receiver includes the corresponding multi-arydecoder 604; after calculating out the symbol posteriori probabilitysequence according to the symbol sequence transmitted by the user, themulti-user demodulator 601 can recover the symbol posteriori probabilitysequence and send it to the multi-ary decoder 604 for decoding, withoutinvolving any conversion of the probability sequence, and therefore, theoperation is simplified;

a user interleaver 605, adapted to interleave the symbol prioriprobability sequences to obtain interleaved symbol priori probabilitysequences, where the user interleaver 605 may be the same as the userinterleaver 503 in FIG. 5; and

a spreader 606, adapted to spread the interleaved symbol prioriprobability sequences to obtain spread symbol priori probabilitysequences, where the spreader 606 may be the same as the spreader 504 inFIG. 5.

The detailed receiving process differs from the first embodiment of thereceiving apparatus only in that the order of the de-interleaving step,the de-spreading step, the interleaving step, and the spreading step ischanged.

Described above is a process of transmitting and receiving signals of aspecific user in a multi-user processing process. It is understandablethat on the basis of the second embodiment, the spreading sequences ofall users may be interleaved finally after the spreading, as shown inFIG. 7. FIG. 7 shows an apparatus for transmitting multi-aryerror-correcting codes in the third embodiment of the present invention.The transmitting apparatus includes:

a multi-ary channel encoder 701, adapted to perform multi-ary encodingfor source data frames of a user to obtain encoded sequences;

a symbol mapper 702, adapted to perform symbol mapping for the encodedsequences to obtain symbol sequences;

a user interleaver 703, adapted to interleave the symbol sequences toobtain interleaved sequences, where the users may use the same ordifferent user interleavers;

a spreader 704, adapted to spread the interleaved sequences to obtainspreading sequences; and

a final interleaver 705, adapted to interleave the spreading sequencesto obtain a final interleaved sequence and output it.

When all users use the same spreader 704, the users need to usedifferent final interleavers 705; when the users use different spreaders704, the users may use the same or different final interleavers 705.

The detailed transmitting process differs from the second embodiment ofthe transmitting apparatus only in that: after spreading sequences areobtained through a spreading step, the spreading sequences of all usersare interleaved through a final interleaver 705 to obtain a finalinterleaved sequence for transmitting.

Likewise, the receiving apparatus needs to be changed accordingly, asshown in FIG. 8. FIG. 8 shows an apparatus for receiving multi-aryerror-correcting codes in the third embodiment of the present invention.The receiving apparatus includes:

a multi-user demodulator 801, adapted to: receive sequences, andcalculate the received sequences to obtain symbol posteriori probabilitysequences;

a final de-interleaver 802, adapted to: receive the symbol posterioriprobability sequences calculated out by the multi-user demodulator, andde-interleave the symbol posteriori probability sequences to obtain afinal de-interleaved symbol posteriori probability sequence, where theprocess executed by the final de-interleaver 802 is an inverse of theprocess executed by the final interleaver 705 in FIG. 7, and thedetailed process is covered by the prior art;

a de-spreader 803, adapted to de-spread the final de-interleaved symbolposteriori probability sequence to obtain de-spread symbol posterioriprobability sequences, where the process executed by the de-spreader 803is an inverse of the process executed by the spreader 704 in FIG. 7, andthe detailed process is covered by the prior art;

a de-interleaver 804, adapted to de-interleave the de-spread symbolposteriori probability sequences to obtain de-interleaved symbolposteriori probability sequences, where the process executed by thede-interleaver 804 is an inverse of the process executed by theinterleaver 703 in FIG. 7, and the detailed process is covered by theprior art;

a multi-ary decoder 805, adapted to: decode the de-interleaved symbolposteriori probability sequences, output symbol priori probabilitysequences, work with a multi-user demodulator 801 to perform iterativeoperations, judge whether the count of iterations reaches a presetthreshold, and output decoding results if the count of iterationsreaches the preset threshold;

a user interleaver 806, adapted to interleave the symbol prioriprobability sequences to obtain interleaved symbol priori probabilitysequences, where the user interleaver 806 may be the same as the userinterleaver 703 in FIG. 7;

a spreader 807, adapted to spread the interleaved symbol prioriprobability sequences to obtain spread symbol priori probabilitysequences, where the spreader 807 may be the same as the spreader 704 inFIG. 7; and

a final interleaver 808, adapted to: receive the spread symbol prioriprobability sequences generated by the spreader 807, interleave thespread symbol priori probability sequences to obtain a final interleavedsymbol priori probability sequence, and send the final interleavedsymbol priori probability sequences to the multi-user demodulator 801,where the final interleaver 808 may be the same as the final interleaver705 in FIG. 7.

The detailed receiving process differs from the second embodiment of thereceiving apparatus only in that: final de-interleaving is performedbefore the de-spreading, and final interleaving is performed after thespreading.

In each of the foregoing embodiments, the transmitting apparatus maycombine with the receiving apparatus into a data transmission system.

In the foregoing embodiments, the multi-user demodulator is adapted tocalculate the received sequences to obtain symbol posteriori probabilitysequences. An exemplary process of calculating the symbol posterioriprobability sequences is as follows:

For brevity, it is assumed that the channel has no memory effect, andthe number of active users in the system is K.

The signals received from K users after passing through the matchingfilter at the front end of the receiver may be expressed as:

$\begin{matrix}{{{r(j)} = {{\sum\limits_{k = 1}^{K}{h_{k}{x_{k}(j)}}} + {n(j)}}}{{j = 1},2,\ldots\mspace{14mu},J}} & (1)\end{matrix}$

where h_(k) is a channel coefficient of user k, and is a real number;n(j) is white Gaussian noise with a variance of σ²=N₀/2; J representsthe length of the transmitted symbol sequence. It is assumed that thechannel coefficient h_(k) is known at the receiver.

Therefore, formula (1) is transformed into:

$\begin{matrix}{{{r(j)} = {{h_{k}{x_{k}(j)}} + {\zeta_{k}(j)}}}{{where},}} & \left( {2a} \right) \\{{{\zeta_{k}(j)} \equiv {{r(j)} - {h_{k}{x_{k}(j)}}}} = {{\sum\limits_{k^{\prime} \neq k}{h_{k^{\prime}}{x_{k^{\prime}}(j)}}} + {n(j)}}} & \left( {2b} \right)\end{matrix}$

is distortion about user k (including interference plus noise) in r(j).According to the central limit theorem, ζ_(k)(j) is similar to aGaussian variable, and r(j) may be represented by a conditional Gaussianprobability density function, namely,

$\begin{matrix}{{P\left( {{r(j)}❘{x_{k}(m)}} \right)} = {\frac{1}{\sqrt{2{{\pi Var}\left( {\zeta_{k}(j)} \right)}}}{\exp\left\lbrack {- \frac{\left( {{r(j)} - \left( {{{h_{k}(j)} \cdot {x_{k}(m)}} + {E\left( {\zeta_{k}(j)} \right)}} \right)} \right)^{2}}{2{{Var}\left( {\zeta_{k}(j)} \right)}}} \right\rbrack}}} & (3)\end{matrix}$

where E(•) represents a mean value function and Var(•) represents avariance function.

According to the Bayes formula,

$\begin{matrix}{{P\left( {{x_{k}(m)}❘{r(j)}} \right)} = {\frac{{P\left( {{r(j)}❘{x_{k}(m)}} \right)}{P\left( {x_{k}(m)} \right)}}{P\left( {r(j)} \right)}.}} & (4)\end{matrix}$

Formula (4) represents the posteriori probability of the transmittedsignal x_(k)(m) when the received signal is r(j). It is assumed that thetransmitted symbol has an equal probability and the received symbol is adefinite value, namely, P(r(j))=1, formula (4) may be simplified belowwhen the modulation mode is M-ary modulation:

$\begin{matrix}{{P\left( {{x_{k}(m)}❘{r(j)}} \right)} = {\frac{P\left( {{r(j)}❘{x_{k}(m)}} \right)}{M}.}} & (5)\end{matrix}$

According to formula (3) and (5), the formula for calculating thetransmitted symbol posteriori probability P(x_(k)(m)|r(j)) is:

$\begin{matrix}{{P\left( {{x_{k}(m)}❘{r(j)}} \right)} = {\frac{1}{M\sqrt{2{{\pi Var}\left( {\zeta_{k}(j)} \right)}}}{{\exp\left\lbrack {- \frac{\left( {{r(j)} - \left( {{{h_{k}(j)} \cdot {x_{k}(m)}} + {E\left( {\zeta_{k}(j)} \right)}} \right)} \right)^{2}}{2{{Var}\left( {\zeta_{k}(j)} \right)}}} \right\rbrack}.}}} & (6)\end{matrix}$

It is to be noted that in the first iteration process, it is generallyassumed that the transmitted symbol priori probability is equal. Whenthe multi-ary decoder performs decoding and outputs the updatedtransmitted symbol priori probability information to the multi-userdemodulator, the multi-user demodulator re-calculates the mean value andthe variance of ζ_(k)(j) according to the information, and obtains theupdated transmitted symbol posteriori probability information.

In other cases, the method for calculating the transmitted symbolposteriori probability may be deduced accordingly.

From the perspective of the transmitting apparatus, in the foregoingembodiments, symbol mapping is performed before the spreading and theinterleaving. Therefore, the quantity of data units is reduced, and theoperation involved in the spreading and interleaving is simplified. Itis understandable that the operation in the spreading and interleavingcan be simplified only if the encoded sequences are combined in acertain way to reduce data units. The following embodiment supposes thatthe sequences are grouped.

As shown in FIG. 9, an apparatus for transmitting multi-aryerror-correcting codes in the fourth embodiment of the present inventionincludes:

a multi-ary channel encoder 901, adapted to perform multi-ary encodingfor source data frames of a user to obtain encoded sequences;

a grouping device 902, adapted to group the encoded sequences to obtaingrouped sequences;

a user interleaver 903, adapted to interleave the grouped sequences toobtain interleaved sequences, where the users may use the same ordifferent user interleavers;

a symbol mapper 904, adapted to perform symbol mapping for theinterleaved sequences to obtain symbol sequences; and

a spreader 905, adapted to spread the symbol sequences to obtainspreading sequences, where the users use different spreaders.

The detailed transmitting process is follows:

The source data frame b_(k) of user k outputs encoded sequences c_(k)after passing through the multi-my channel encoder 901.

The encoded sequence is expressed as c_(k)={c_(k,0), c_(k,1), . . . ,c_(k,m), . . . }, where each element corresponds to a bit. It is assumedthat the multi-ary channel encoder 901 is defined on a Galois fieldGF(2^(q)), where q is a natural number. Every q bits in the codesequence c_(k) corresponds to a specific symbol.

The grouping device 902 groups the encoded sequences c_(k) using thesymbol as a unit, and outputs grouped sequences s_(k).

s_(k)={s_(k,0), s_(k,1), . . . , s_(k,m), . . . }, where each element ins_(k) corresponds to a group of bits {c_(k,qm), c_(k,qm+1), . . . ,c_(k,qm+q−1)}.

After s_(k) passes through the user interleaver 903, an interleavedsequence v_(k) is output.

The length of v_(k) is the same as the length of s_(k), where the userinterleaver 903 can be the interleaver used in the existing IDMA systemor not.

After v_(k) passes through the symbol mapper 904, a symbol sequencex_(k) is output.

In the mapping process, a group of bits represented by each element ofv_(k) is mapped to a specific symbol.

After x_(k) passes through the spreader 905, a spreading sequence t_(k)is output.

Described above is a process of transmitting and receiving signals of aspecific user in a multi-user processing process. It is understandablethat on the basis of the fourth embodiment, the spreading sequences ofall users may be interleaved finally after the spreading, as shown inFIG. 10. FIG. 10 shows an apparatus for transmitting multi-myerror-correcting codes in the fifth embodiment of the present invention.The transmitting apparatus includes:

a multi-ary channel encoder 1001, adapted to perform multi-ary codingfor source data frames of a user to obtain encoded sequences;

a grouping device 1002, adapted to group the encoded sequences to obtaingrouped sequences;

a user interleaver 1003, adapted to interleave the grouped sequences toobtain interleaved sequences, where the users may use the same ordifferent user interleavers;

a symbol mapper 1004, adapted to perform symbol mapping for theinterleaved sequences to obtain symbol sequences;

a spreader 1005, adapted to spread the symbol sequences to obtainspreading sequences; and

a final interleaver 1006, adapted to interleave the spreading sequencesto obtain a final interleaved sequence and output it.

When all users use the same spreader 1005, the users need to usedifferent final interleavers 1006; when the users use differentspreaders 1005, the users may use the same or different finalinterleavers 1006.

The detailed transmitting process differs from the fourth embodiment ofthe transmitting apparatus only in that: after the spreading, thespreading sequences of all users are interleaved to obtain a finalinterleaved sequence and the final interleaved sequence is sent.

In the foregoing embodiments, the signals from a specific user aretransmitted and received in the multi-user processing process, namely,the schematic diagrams above illustrates the process of transmitting andreceiving signals of a specific user. In practice, the multi-userdemodulator in the receiving apparatus is connected with more than oneuser, as shown in FIG. 11. FIG. 11 is based on the third embodiment ofthe apparatus for receiving multi-ary error-correcting codes, but it isunderstandable that the figure may be based on other embodiments of thereceiving apparatus.

Relevant methods are provided herein. A method for transmittingmulti-ary error-correcting codes provided in an embodiment of thepresent invention includes:

performing multi-ary coding for source data frames of a user to obtainencoded sequences;

performing symbol mapping for the encoded sequences to obtain symbolsequences;

preprocessing the symbol sequences; and

transmitting the preprocessed sequences.

The preprocessing comes in the following two types:

(A) After the symbol mapping, interleaving occurs before spreading:

As shown in FIG. 12, a method for transmitting multi-aryerror-correcting codes in the first embodiment of the present inventionincludes the following blocks:

1201: Receive source data frames sent by the user.

1202: Perform multi-ary coding for the source data frames to obtainencoded sequences.

1203: Perform symbol mapping for the encoded sequences to obtain symbolsequences.

1204: Interleave the symbol sequences to obtain interleaved sequences.

1205: Spread the interleaved sequences to obtain spreading sequences andtransmit them.

For the instances and detailed description about the process, see thedescription about the embodiments of the apparatus for transmittingmulti-ary error-correcting codes above.

It is understandable that in this embodiment, the spreading sequencesmay be interleaved finally before being transmitted.

(B) After the symbol mapping, spreading occurs before interleaving:

As shown in FIG. 13, a method for transmitting multi-aryerror-correcting codes in the second embodiment of the present inventionincludes the following blocks:

1301: Receive source data frames sent by the user.

1302: Perform multi-ary coding for the source data frames to obtainencoded sequences.

1303: Perform symbol mapping for the encoded sequences to obtain symbolsequences.

1304: Spread the symbol sequences to obtain spreading sequences.

1305: Interleave the spreading sequences to obtain interleaved sequencesand transmit them.

For the instances and detailed description about the process, see thedescription about the embodiments of the apparatus for transmittingmulti-ary error-correcting codes above.

A method for receiving multi-ary error-correcting codes is put forwardherein. As shown in FIG. 14, a method for receiving multi-aryerror-correcting codes in the first embodiment of the present inventionincludes the following blocks:

1401: Calculate received sequences to obtain symbol posterioriprobability sequences.

1402: De-spread the symbol posteriori probability sequences to obtainde-spread symbol posteriori probability sequences.

1403: De-interleave the de-spread symbol posteriori probabilitysequences to obtain de-interleaved symbol posteriori probabilitysequences.

1404: Decode the de-interleaved symbol posteriori probability sequences,output symbol priori probability sequences, and then perform iterativeoperations for the symbol priori probability sequences, and performblock 1406.

1405: Work with a multi-user demodulator to perform iterativeoperations.

1406: Interleave the symbol priori probability sequences to obtaininterleaved symbol priori probability sequences.

1407: Spread the interleaved symbol priori probability sequences toobtain spread symbol priori probability sequences, and perform iterativeoperations through block 1405.

1408: Judge whether the count of iterations reaches the presetthreshold; if the count of iterations reaches the preset threshold,perform block 1409, otherwise, perform block 1404.

1409: After the iteration is complete, output the decoding results.

For the instances and detailed description about the process, see thedescription about the embodiments of the apparatus for receivingmulti-ary error-correcting codes above.

In this embodiment, the following block may be added between block 1401and block 1402: De-interleave the symbol posteriori probabilitysequences to obtain a final de-interleaved symbol posteriori probabilitysequence, and send the final de-interleaved symbol posterioriprobability sequence to the de-spreader.

The additional blocks occur when the transmitting method includes afinal interleaving receiving process.

In this embodiment, the following block may be added after block 1404:Interleave the spread symbol priori probability sequences to obtain afinal interleaved symbol priori probability sequence, and send the finalinterleaved symbol priori probability sequence to the multi-userdemodulator.

As shown in FIG. 15, a method for receiving multi-ary error-correctingcodes in the second embodiment of the present invention includes thefollowing blocks:

1501: Calculate received sequences to obtain symbol posterioriprobability sequences.

1502: De-interleave the symbol posteriori probability sequences toobtain de-interleaved symbol posteriori probability sequences.

1503: De-spread the de-interleaved symbol posteriori probabilitysequences to obtain de-spread symbol posteriori probability sequences.

1504: Decode the de-spread symbol posteriori probability sequences,output symbol priori probability sequences, and then perform iterativeoperations for the symbol priori probability sequences, and performblock 1506.

1505: Work with a multi-user demodulator to perform iterativeoperations.

1506: Spread the symbol priori probability sequences to obtain spreadsymbol priori probability sequences.

1507: Interleave the spread symbol priori probability sequences toobtain interleaved symbol priori probability sequences, and performiterative operations through block 1505.

1508: Judge whether the count of iterations reaches the presetthreshold; if the count of iterations reaches the preset threshold,perform block 1509, otherwise, perform block 1504.

1509: After the iteration is completed, output the decoding results.

For the instances and detailed description about the process, see thedescription about the embodiments of the apparatus for receivingmulti-ary error-correcting codes above.

It is understandable to those skilled in the art that all or part of theblocks of the foregoing embodiments may be implemented by hardwareinstructed by a computer program. The program may be stored in acomputer-readable storage medium. The storage medium may be a Read-OnlyMemory (ROM), magnetic disk, or Compact Disk (CD).

Elaborated above are an apparatus for transmitting multi-aryerror-correcting codes, an apparatus for receiving multi-aryerror-correcting codes, a data transmission system, and relevant methodsunder the present invention. Although the invention is described throughsome exemplary embodiments, the invention is not limited to suchembodiments. It is apparent that those skilled in the art can makemodifications and variations to the invention without departing from thespirit and scope of the invention. The invention is intended to coversuch modifications and variations provided that they fall in the scopeof protection defined by the following claims or their equivalents.

What is claimed is:
 1. An apparatus for receiving multi-aryerror-correcting codes, comprising: a multi-user demodulator, adapted toreceive sequences and calculate the received sequences to obtain symbolposteriori probability sequences; a de-spreading and de-interleavingunit, adapted to perform de-spreading and de-interleaving for the symbolposteriori probability sequences to obtain de-spread and de-interleavedsequences, the de-spreading and de-interleaving unit comprising, ade-interleaver, adapted to de-interleave the symbol posterioriprobability sequences to obtain the de-interleaved symbol posterioriprobability sequences, and a de-spreader, adapted to de-spread thede-interleaved symbol posteriori probability sequences to obtain thede-spread symbol posteriori probability sequences; a multi-ary decoder,adapted to decode the de-spread and de-interleaved sequences, outputsymbol priori probability sequences, work with the multi-userdemodulator to perform iterative operations, judge whether a count ofiterations reaches a preset threshold, and output decoding results ifthe count of the iterations reaches the preset threshold; and aspreading and interleaving unit, adapted to spread and interleave thesymbol priori probability sequences, and send the spread and interleavedsequences to the multi-user demodulator to undergo joint iterativeoperations.
 2. The apparatus for receiving multi-ary error-correctingcodes of claim 1, further comprising: a final de-interleaver, adaptedto: receive the symbol posteriori probability sequences calculated outby the multi-user demodulator, de-interleave the symbol posterioriprobability sequences to obtain a final de-interleaved symbol posterioriprobability sequence, and send the final de-interleaved symbolposteriori probability sequence to the de-spreader; and a finalinterleaver, adapted to: receive the spread symbol priori probabilitysequences generated by the spreader, interleave the spread symbol prioriprobability sequences to obtain a final interleaved symbol prioriprobability sequence, and send the final interleaved symbol prioriprobability sequence to the multi-user demodulator.
 3. The apparatus forreceiving multi-ary error-correcting codes of claim 1, wherein: themulti-ary decoder decodes the de-spread symbol posteriori probabilitysequences; the spreading and interleaving unit comprises: a spreader,adapted to spread the symbol priori probability sequences to obtain thespread symbol priori probability sequences; and a user interleaver,adapted to interleave the spread symbol priori probability sequences toobtain the interleaved symbol priori probability sequences, and send theinterleaved symbol priori probability sequences to the multi-userdemodulator to undergo joint iterative operations.
 4. A datatransmission system, comprising an apparatus for transmitting multi-aryerror-correcting codes and an apparatus for receiving multi-aryerror-correcting codes, wherein: the apparatus for transmittingmulti-ary error-correcting codes comprises: a multi-ary channel encoder,adapted to perform multi-ary encoding for source data frames of a userto obtain encoded sequences; a symbol mapper, adapted to perform symbolmapping for the encoded sequences to obtain symbol sequences; and aspreading and interleaving unit, adapted to spread and interleave thesymbol sequences, the spreading and interleaving unit comprising, aspreader, adapted to spread the symbol sequences to obtain spreadingsequences, and an interleaver, adapted to interleave the spreadingsequences to obtain interleaved sequences; and the apparatus forreceiving multi-ary error-correcting codes comprises: a multi-userdemodulator, adapted to receive sequences and calculate the receivedsequences to obtain symbol posteriori probability sequences; ade-spreading and de-interleaving unit, adapted to perform de-spreadingand de-interleaving for the symbol posteriori probability sequences; amulti-ary decoder, adapted to: decode the de-spread and de-interleavedsequences, output symbol priori probability sequences, work with themulti-user demodulator to perform iterative operations, judge whether acount of iterations reaches a preset threshold, and output decodingresults if the count of the iterations reaches the preset threshold; anda spreading and interleaving unit, adapted to spread and interleave thesymbol priori probability sequences, and send the spread and interleavedsequences to the multi-user demodulator.
 5. A method for receivingmulti-ary error-correcting codes, comprising: calculating receivedsequences to obtain symbol posteriori probability sequences;de-interleaving the symbol posteriori probability sequences to obtainde-interleaved symbol posteriori probability sequences; de-spreading thede-interleaved symbol posteriori probability sequences to obtainde-spread symbol posteriori probability sequences; decoding thede-spread symbol posteriori probability sequences, outputting symbolpriori probability sequences, working with a multi-user demodulator toperform iterative operations, judging whether a count of iterationsreaches a preset threshold, and outputting decoding results if the countof the iterations reaches the preset threshold; spreading the symbolpriori probability sequences to obtain spread symbol priori probabilitysequences; and interleaving the spread symbol priori probabilitysequences to obtain interleaved symbol priori probability sequences, andsending the interleaved symbol priori probability sequences to themulti-user demodulator to undergo joint iterative operations.
 6. Anapparatus for receiving multi-ary error-correcting codes, comprising: amulti-user demodulator, adapted to receive sequences and calculate thereceived sequences to obtain symbol posteriori probability sequences; ade-spreading and de-interleaving unit, adapted to perform de-spreadingand de-interleaving for the symbol posteriori probability sequences toobtain de-spread and de-interleaved sequences, the de-spreading andde-interleaving unit comprising: a de-spreader, adapted to de-spread thesymbol posteriori probability sequences to obtain de-spread symbolposteriori probability sequences, and a de-interleaver, adapted tode-interleave the de-spread symbol posteriori probability sequences toobtain de-interleaved symbol posteriori probability sequences; amulti-ary decoder, adapted to decode the de-interleaved symbolposteriori probability sequences, output symbol priori probabilitysequences, work with the multi-user demodulator to perform iterativeoperations, judge whether a count of iterations reaches a presetthreshold, and output decoding results if the count of the iterationsreaches the preset threshold; a spreading and interleaving unit, adaptedto spread and interleave the symbol priori probability sequences, andsend the spread and interleaved sequences to the multi-user demodulatorto undergo joint iterative operations, the spreading and interleavingunit comprising: a user interleaver, adapted to interleave the symbolpriori probability sequences to obtain interleaved symbol prioriprobability sequences, and a spreader, adapted to spread the interleavedsymbol priori probability sequences to obtain spread symbol prioriprobability sequences, and send the spread symbol priori probabilitysequences to the multi-user demodulator to undergo joint iterativeoperations; a final de-interleaver, adapted to: receive the symbolposteriori probability sequences calculated out by the multi-userdemodulator, de-interleave the symbol posteriori probability sequencesto obtain a final de-interleaved symbol posteriori probability sequence,and send the final de-interleaved symbol posteriori probability sequenceto the de-spreader; and a final interleaver, adapted to: receive thespread symbol priori probability sequences generated by the spreader,interleave the spread symbol priori probability sequences to obtain afinal interleaved symbol priori probability sequence, and send the finalinterleaved symbol priori probability sequence to the multi-userdemodulator.
 7. A method for receiving multi-ary error-correcting codes,comprising: calculating received sequences to obtain symbol posterioriprobability sequences; de-spreading the symbol posteriori probabilitysequences to obtain de-spread symbol posteriori probability sequences;de-interleaving the de-spread symbol posteriori probability sequences toobtain de-interleaved symbol posteriori probability sequences; decodingthe de-interleaved symbol posteriori probability sequences, outputtingsymbol priori probability sequences, working with a multi-userdemodulator to perform iterative operations, judging whether a count ofiterations reaches a preset threshold, and outputting decoding resultsif the count of the iterations reaches the preset threshold;interleaving the symbol priori probability sequences to obtaininterleaved symbol priori probability sequences; spreading theinterleaved symbol priori probability sequences to obtain spread symbolpriori probability sequences, and sending the spread symbol prioriprobability sequences to the multi-user demodulator to undergo jointiterative operations; and wherein after calculating the receivedsequences to obtain the symbol posteriori probability sequences, themethod comprises: de-interleaving the symbol posteriori probabilitysequences to obtain a final de-interleaved symbol posteriori probabilitysequence, and sending the final de-interleaved symbol posterioriprobability sequence to a de-spreader.
 8. A method for receivingmulti-ary error-correcting codes, comprising: calculating receivedsequences to obtain symbol posteriori probability sequences;de-spreading the symbol posteriori probability sequences to obtainde-spread symbol posteriori probability sequences; de-interleaving thede-spread symbol posteriori probability sequences to obtainde-interleaved symbol posteriori probability sequences; decoding thede-interleaved symbol posteriori probability sequences, outputtingsymbol priori probability sequences, working with a multi-userdemodulator to perform iterative operations, judging whether a count ofiterations reaches a preset threshold, and outputting decoding resultsif the count of the iterations reaches the preset threshold;interleaving the symbol priori probability sequences to obtaininterleaved symbol priori probability sequences; spreading theinterleaved symbol priori probability sequences to obtain spread symbolpriori probability sequences, and sending the spread symbol prioriprobability sequences to the multi-user demodulator to undergo jointiterative operations; and wherein after decoding the de-interleavedsymbol posteriori probability sequences and outputting the symbol prioriprobability sequences, the method comprises: interleaving the spreadsymbol priori probability sequences to obtain a final interleaved symbolpriori probability sequence, and ending the final interleaved symbolpriori probability sequence to the multi-user demodulator.